1. Field of the Invention
The invention relates to a used paper processing apparatus, and more particularly to a used paper processing technique for processing used documents and used paper such as confidential papers from government authorities and private enterprises and private letters and used paper from general household, while effectively preventing leak or disclosure of confidential information and personal information printed or written on the paper documents.
2. Description of the Related Art
In routine works at public offices and private companies, various documents containing confidential information such as company information including customer information, personal information, project schemes, etc., and plans, designs, diagrams and so on are used and managed, and in daily household life, letters and postcards bearing address, personal name and other private information, electricity and gas meter bills and other personal papers are handled, and after use, these documents are discarded as used paper.
In our modern electronic society promoted by information technology, it is essential to prevent leak and disclosure of confidential information written in used paper such as company information including customer information, design drawings, etc., and private information including personal names and addresses, etc., and preventive measures and technology are being developed intensively for this purpose.
Among them, the shredder is used widely both in offices and general household, as indispensable means for preventing leak of confidential information and important personal information. The shredder has a mechanism of cutting used paper to be put into the discard into small pieces (see, for example, Japanese Patent Application Laid-Open No. 62-42752), and characters and diagrams printed or written in used paper can be shredded into illegible small pieces, and leak or disclosure of confidential information or important private information composed of characters and diagrams can be prevented effectively.
On the other hand, a surprising technical progress makes it possible to restore the original documents from shredded paper pieces, and reproduce and collect the printed confidential information. It is now proved that the reliability of shredder so far believed to prevent leak of confidential information is not perfect.
Besides, since the shredder is intended to protect the confidential information, the shredded paper pieces must be discarded.
In addition to the conventional shredder for cutting used paper into small pieces, a wet process shredder is developed for tearing used paper into small pieces while adding a small amount of water (see, for example, Japanese Patent Application Laid-Open No. 6-134331), torn chips of used paper processed by this shredder are sent to a paper recycling plant, and used as material for recycled paper.
Torn chips by wet process shredder are pulp, not in the form of paper, and original documents will not be restored as in the case of cut chips from conventional shredder, and confidential information can be protected.
However, the wet process shredder is very bulky as compared with ordinary shredder, and requires a large space for installation, and its use is limited only to a huge office producing a huge volume of used paper, and it is not suited to small office, shop or general household not having enough space for installation or limited in the output of used paper. If the torn chips are used as material for recycle paper, paper can be processed only in a large plant, and the paper processing cost is high, and it is not economical.